Natural resources provide substantially all of man's energy source materials in the form of fossil fuels, wood and other types of plant life.
Wood and coal have been a principle source of fuel for hundreds of years. Within the last one hundred years, petroleum has become the overwhelming primary commodity for the generation of energy. Petroleum has had the advantages of low cost and ease of transportation and storage because of its liquid consistency. Further, petroleum is readily amenable to fractionation and conversion into a variety of valuable industrial products such as fuels, building products, chemical intermediates and the like.
Recent international economic developments have signaled the inevitable decline of petroleum as the world's supreme industrial commodity. The price of raw petroleum has increased several fold. Also, the consumption of petroleum has been increasing exponentially and concomitantly the world petroleum supply has diminished to less than several decades of proven reserves.
Governments and industrial concerns on a priority basis are dedicating increased attention to alternatives to petroleum as sources for fuels and chemical intermediates, i.e., coal and wood. Substantial reserves of coal exist in highly industrialized countries, and wood is both plentiful and replenishable worldwide.
Since most current energy utilization technology requires liquid energy media, it has become an important research and development objective to provide innovative means to convert coal and wood into liquid sources of potential energy.
It was recognized by early workers that both coal and wood can be liquified by controlled heating in the substantial absence of oxygen. The conversion products are a liquid, gas and a char. Because of the new compelling economic factors, the technology of coal liquefaction and gasification has been expanding at an accelerated pace. Pioneer developments in the field are represented by Lurgi and Fischer-Tropsch technology. More recent advances in coal liquefaction are described in U.S. Pat. Nos. 1,904,586; 1,955,041; 1,996,009; 2,091,354; 2,174,184; 2,714,086; 3,375,188; 3,379,638; 3,607,718; 3,640,816; 3,642,608; 3,705,092; 3,849,287; 3,870,621; inter alia.
The destructive distillation of wood to produce charcoal, oils and gases has been known for centuries. In a recent publication, an American company reported a process for producing as much as two barrels of oil per ton of tree bark by a controlled pyrolysis process. The United States Bureau of Mines, in publication Number 8013 entitled "Conversion of Cellulosic Wastes To Oil", reports 90-99 weight percent conversion of sawdust with 40-60 weight percent yields of oil by reaction with synthesis gas at a temperature of 250.degree.-425.degree. C and a pressure of 1500-4000 psig, in the presence of water and an inorganic catalyst.
There remains a pressing need for new technology for the conversion of coal and wood into liquid carbonaceous products to complement and to enhance conventional petroleum derived energy and chemical applications. Innovative processes for liquefaction of coal and wood are required which are not dependent on high pressures or reducing gases or catalysts for efficient and economic liquefaction of coal and wood.
It is an object of the present invention to provide an improved method for converting solid carbonaceous materials into gaseous and liquid derivatives having application as fuels and chemical intermediates.
It is another object of the present invention to provide a process for the liquefaction of carbonaceous materials without the use of high pressures, reducing gases, or catalysts.
It is another object of the present invention to solubilize wood and wood/coal mixture to form flowable pitchlike compositions which are directly applicable as liquid fuels.
It is a further object of the present invention to upgrade low value refractory petroleum residua from refinery operations into gaseous and liquid fuel media.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.